Add tests for contentnode_slim endpoint
Add tests for contentnode_slim endpoint

lyw07/kolibri,learningequality/kolibri,indirectlylit/kolibri,mrpau/kolibri,DXCanas/kolibri,lyw07/kolibri,DXCanas/kolibri,DXCanas/kolibri,lyw07/kolibri,DXCanas/kolibri,mrpau/kolibri,learningequality/kolibri,lyw07/kolibri,learningequality/kolibri,learningequality/kolibri,mrpau/kolibri,indirectlylit/kolibri,indirectlylit/kolibri,indirectlylit/kolibri,mrpau/kolibri